eeeWhitneyCameronn(Cotten),amanwithastrongaffectionforhissister-in-law(Peters).Whenoneofherstepchildrendies,it'srevealedthatthechildwaspoisonedtodeath.Whitneysuspectshissister-in-lawcommittedthemurderandisafraidthatherothersonmaybeindanger.Thefilmclimaxesduringanoceanvoyageaboardacruiseship.